Conventionally, there has been known an energy storage module which includes: energy storage cells; a pair of side-portion fastening frames which sandwiches the energy storage cells therebetween in a width direction; and insulators which are disposed between the energy storage cells and side-portion fastening frames (see JP-A-2015-99649).
To be more specific, the energy storage module is assembled such that the plurality of energy storage cells and the end plates are stacked in a stacking direction and, in such a state, both end portions of the pair of side-portion fastening frames made of a metal plate-like member in a stacking direction are fastened to both end portions of the pair of end plates in a width direction. Further, in the energy storage module, the plurality of energy storage cells are sandwiched by the pair of insulators from both sides in a width direction, and the plurality of energy storage cells are sandwiched and fixed by the pair of side-portion fastening frames from the outside in the width direction.
In this manner, the energy storage module has the simple structure where the insulators are simply sandwiched between the plurality of the energy storage cells and the side-portion fastening frames. Accordingly, during the use of the energy storage module, there is a case where rain water or the like (water) is adhered to a surface of the side-portion fastening frame which opposedly faces the energy storage cells or a condensate or the like (water) is generated on the opposedly facing surface. In such a case, there is a possibility that water leaks out from between the insulator and the side-portion fastening frame and flows toward an energy storage battery cell side so that electric resistance between the energy storage cells or electric resistance between the energy storage cell and the side-portion fastening frame becomes small due to such water.